1. Field of the Invention
The present invention belongs to the fields of agricultural and organic chemistry, and provides to the art a series of new 4-(halo-branched-alkyl or silyl)pyridazines, which are fungicides for the protection of plants from harmful pathogens. The compounds are effective against Phycomycetous fungi, which include some of the most injurious plant pathogens. In particular, the compounds are effective against Phytophthora infestans, which is the causative organism of late blight of potato and tomato and which caused the terrible potato famine of 1845.
2. State of the Art
Halo-branched-alkyl heterocycles have not previously been studied in the plant protection art. Earlier work has focused on compounds such as those of U.S. Pat. No. 3,883,530, which teaches di- and trichloromethylpyridazines having from 2 to 3 chlorine atoms on the heterocyclic ring. U.S. Pat. No. 4,263,297 shows a 3-trichloromethylpyridazine having an alkoxy group at the 6-position. Both patents describe their compounds as fungicides and bactericides.
West German Patent application No. 2,531,476 shows 3,6-dichloro-4-trichloromethylpyridazine, also described as a fungicide.
Dow Chemical formerly sold a fungicide, active against Phycomycetes, called pyroxyfur, which is 2-chloro-6-(furan-2-ylmethoxy)-4-trichloromethylpyridine.